Electrophotographic copying machines appear useful for preparing offset printing plates by a simple method. However, the offset printing plates need to bear mirror images, whereas usual electrophotographic copying machines produce normal images only.
On the other hand, although it is possible to design a copying machine specifically for preparing offset printing plates only, the machine will predominantly be of the same construction as copying machines for producing usual copies, so that it is inefficient to prepare a copying machine for offset printing plates and a copying machine for usual copies.